


Magnus the Magical Merman

by Takara_Phoenix



Series: Phoe's Writer's Month 2020 [8]
Category: Shadowhunters (TV)
Genre: Anal, Bottom Jace, Canon Divergence, Double Penetration, Explicit Sexual Content, Fluff, Hurt/Comfort, Jace Raised in the Circle, Jace develops an obsession with Magnus' tentacles, M/M, Merman Magnus Bane, Mutual Saving, Octopus Merman, Oral, Slash, Tentacle Sex, Top Magnus, Triple Penetration, Writer's Month 2020
Language: English
Status: Completed
Published: 2020-08-08
Updated: 2020-08-08
Packaged: 2021-03-06 00:02:22
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 7,068
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25784089
Author URL: https://archiveofourown.org/users/Takara_Phoenix/pseuds/Takara_Phoenix
Summary: On board of the Morning Star, Jace meets a captive merman warlock – Magnus Bane. They break out together and, not knowing where to go, Jace stays with Magnus and slowly builds up a new life for himself.
Relationships: Magnus Bane/Jace Wayland
Series: Phoe's Writer's Month 2020 [8]
Series URL: https://archiveofourown.org/series/1859461
Comments: 8
Kudos: 178
Collections: Writer's Month 2020





	Magnus the Magical Merman

Shadowhunters || Jagnus || Magnus the Magical Merman || Jagnus || Shadowhunters

Title: Magnus the Magical Merman – Writer's Month 2020

Fandom: Shadowhunters: The Mortal Instruments

Disclaimer: All rights to the _Shadowhunters_ show reserved to Ed Decter, the books the show is based off and its characters belong to Cassandra Clare. This fanfiction on the other hand is entirely mine. No money is made with this, though reviews are more than welcomed.

Tags: m/m, hurt/comfort, fluff, tentacles, explicit intercourse, anal, oral, double/triple penetration

Main Pairing: Magnus/Jace

Shadowhunters Characters: Jonathan Christopher 'Jace' Herondale, Magnus Bane

Writer's Month Prompt: eight

Summary: On board of the Morning Star, Jace meets a captive merman warlock – Magnus Bane. They break out together and, not knowing where to go, Jace stays with Magnus.

**Magnus the Magical Merman**

_Writer's Month 2020_

"Hello, gorgeous. You seem to be everybody's favorite punching back."

Jace wiped the blood off the corner of his mouth and looked up. In the cell next to him was a large water-tank and inside, a merman. Long, purple tentacles wrapping around the bars of the cage and swirling inside the water. The man had his arms crossed over the rim of the water-tank, resting his chin on top of his arms. He had one elegant eyebrow cocked, a bemused look on his handsome face.

"It's called training. Makes me stronger", muttered Jace. " Special treatment for the boss' son."

He rested his head against the bars of the cage, head tilted back so he could look up at the merman. Jace had never seen a merman before, much less one with an octopus lower half. Valentine had only recently caught this one. He looked... fascinating. Very handsome; the face, those golden eyes and the well-groomed goatee. Maybe Jace had been hit on the head a bit too often lately. He really had other things on his mind than handsome prisoners. Sighing tired, he ran his fingers through his hair.

"Daddy issues, mh? I feel you on that", chuckled the man. "What's your name, gorgeous?"

"Jace..." replied Jace after a moment. "What's your story?"

"Got myself captured when trying to protect my people. These... bastards... have been fishing for merpeople and trying to capture the young", sighed the other. "Name's Magnus."

"Magnus... the Magnificent, Magical Merman...", whispered Jace slowly.

"The one and only. Did not give myself that nickname though", laughed Magnus.

Jace had heard about him. A recluse warlock, born to a mermaid. Merpeople already held strong magic, but to be the child of a higher demon _and_ a mermaid; he was incredibly powerful. Jace wondered how his father had managed to capture this one – Magnus seemed to _truly_ care about his people. It was terrifying to think what Valentine was going to do with him, or them.

"What about you? Golden boy in your own cage. What's your story?", asked Magnus after a bit.

"Disappointed dad and now I get to pay the price", muttered Jace with a half-shrug, wincing as it irritated his hurt shoulder. "He likes to remind me of my place."

"Ah, yes. Beatings often make people very enthusiastic to join your cause", drawled Magnus.

Jace huffed out a small laugh at that. The merman was funny. Laughing wasn't good with his bruised ribs though. Holding his side, he slowly tried to lay down and close his eyes, for as long as his father would allow it. The sound of the water sloshing in the tank was oddly soothing.

/break\

"You should consider a relocation, little Shadowhunter", noted Magnus the next time they saw each other. "Got out of the cage and yet here you are, with a new bruise on that pretty face."

Jace made a grimace that was supposed to be a sarcastic smile, but the bruise prevented it from really conveying all the sarcasm. Slowly, Jace rubbed his chin, where it hurt.

"What can I say. Work hazard", muttered Jace.

Magnus made a little noise, one that Jace didn't know to interpret. He shouldn't do this anyway. He shouldn't be talking to the prisoners, that only made it hurt more when he saw them being used, tortured or killed and there was nothing he could do. He was powerless here; his bruised state should really be proof enough. When he didn't obey, he'd just be punished.

"Stop doing this", requested Jace in a tired voice. "Stop... flirting with me. I know what you're doing. You want to make me help you escape. And I understand that. But... look at my face. I help a highly important prisoner escape and what do you think will happen to me? I'm sorry, I have to think about my own safety too."

"Oh, pretty boy", whispered Magnus softly, looking amused as he leaned in closer. "I'm not saying 'let me out of this cage and suffer the consequences'. I'm saying... save me and save yourself."

"...What?", asked Jace, voice breaking just a little bit.

"You help me out of here and we're going to leave together", elaborated Magnus.

"No", grunted Jace, jerking his head and backing off. "I can't. He'll find me. He always does."

"Help me and I'll help you", stated Magnus firmly, eyes ablaze. "If you help me out of here, I will help you out there. I'll make _sure_ he will _never_ find you, never _hurt_ you again."

Jace stumbled, staring at Magnus with that impossible feeling of blossoming hope in his chest.

/break\

Who would have thought the pretty little eye-candy would actually be Magnus' salvation? Together, the two of them escaped the Morning Star. It was quite the fight and Jace went down bleeding heavily from a head-wound. The boy was lucky Magnus was with him – and a merman – because he could wrap his tentacles firmly and securely around Jace to hold him close and carry him to safety, a bubble of air stabilized by magic. Otherwise the boy would have drowned.

Magnus considered his options and brought Jace with him to his underwater palace – a cave in an air-pocket, beautifully decorated and highly modern because really, he was a merman, not a caveman. He needed his Netflix, running water and heating. From the inside, no one could tell that this was actually an underwater cave, thanks to magic. State of the art living, in style.

He sighed softly as he laid a cold, wet cloth on Jace's forehead. The blonde was still knocked out cold, Magnus had treated his injuries and put him to rest in a quickly summoned guest bed. For a few minutes, Magnus had busied himself with cleaning up, restocking the fridge with the help of a bit of magic, but he was soon drawn back to the blonde's bedside.

"Hng... My head is killing me..."

Smiling bemused, Magnus got more comfortable, leaning back against the headboard of the bed. He watched how Jace slowly came to it. Those pretty eyes were revealed to him, all gold and blue as they looked at Magnus and recognition set in. This one really was easy on the eyes.

"Easy, sweetheart", whispered Magnus gently. "You were wounded during our escape."

"Escape. Yeah. I... I remember that", sighed Jace, slowly laying back down.

He closed his eyes, pulling the cold cloth down to cover his eyes. "Well, at least you remember. So I assume the head injury isn't as bad as is bled. Very good. I trust you'll be fine on your own."

Magnus got up, looking pleased. He smiled bemused when the blonde went stiff and stared at him with something akin to dread. Magnus paused for a moment, realizing what Jace was thinking.

" _Here_. You will be fine on your own here, for a couple of hours", clarified Magnus, smile softening. "I have to tell my people that I'm back and I have to put some precautions in place. Here, sandwiches and some water, rest some until I get back."

He used his magic to summon a plate and a glass on the nightstand. Jace turned his head to look at it, nodding carefully, looking a bit embarrassed by his initial reaction. Oh dear, Magnus was growing decidedly too fond of the pretty blonde. Abandoned and abused, Jace woke his protective nature. He wouldn't be able to help the Shadowhunter if the blonde hadn't been willing to be helped. Jace _wanted_ out, so Magnus had been able to help him. He hoped he'd be able to help the blonde more, now that the Shadowhunter was here in Magnus' home.

"Thank... you", whispered Jace after a moment.

"We made a deal. You kept your end of the bargain, I'll keep mine. Now rest, pretty boy."

/break\

The second time Jace woke up, he was alone. It was a bit disappointing, because waking up to Magnus' gorgeous face had been very nice earlier. However, the merman _had_ said he was going to be gone for a couple hours. His stomach rumbled so he reached for the sandwich and devoured it in record time. Getting food on the Morning Star had been something up to his father's fancy.

Once he was sated, Jace forced himself out of bed, even though he was still in pain. He needed to use this opportunity to map out where he was. It was instinct, years of training beaten into him. It took longer than normal, because the pain slowed him down. Outside the room he woke up in was a hall – another guest room, a room that looked like the master bedroom, next to it a locked room he couldn't enter, a huge bathroom at the end of the hall and down the opposite end, the hall ended in a living room. Also large. Modern. Many candles lit up the room, which made sense – the lack of windows, the cold walls; Jace had already figured out that they were in a cave of sorts. Beyond the living room was a fancy kitchen and one last room. Well, less a room, more like an entrance hall. What Jace had assumed to be the main entrance was a door leading to a room with a giant pool. A pool so deep, Jace couldn't see the bottom. So that was where they were. An underwater cave.

Too many unknowns. He didn't know how long the underwater tunnel would be, he didn't know how deep below the surface the cave's exit would be, he didn't know how far out from the main land he'd emerge even _if_ all of these variables would work out in his favor.

That didn't sit right with him. He hated not knowing an exit. Just like on the ship. Rationally, he knew he was safe – well, he _suspected_ he was safe; he barely knew Magnus for a few days, who knew just how safe he was going to be. Still, Jace was fairly sure he was safer here than there.

Yet once again he found himself at the mercy of someone with more _power_ than him. This all-powerful warlock. If he changed his mind now, Jace would be out on the streets – and within days, Valentine and the Circle would find him. One time, Jace had made it _nearly_ all the way to the New York Institute to ask for help and shelter, he had seen two Shadowhunters come out for patrol, both dark-haired, one a boy with a bow strapped to his back, the girl with long curls. He had been _so close_ to them, if he had yelled out, they would have heard him. And then he was knocked out and dragged back to his own personal hell and he had to suffer the consequences for his insolence.

He was _so_ very tired of suffering. Part of him was hopeful. Hopeful that perhaps his suffering would end, that perhaps Magnus would... truly, _genuinely_ help him. The fact that Jace was here, with food and his wounds patched up, instead of drifting alone in the ocean...? It left him hopeful.

Sighing softly, Jace crawled back into the bed. He closed his eyes contently as the soft, comfortable bed embraced him. This was so... nice. He wasn't used to nice. He had a cod in his small cabin in the ship. Comfort made people weak, was what Valentine always said. But Magnus seemed insanely powerful even with all the comfort, so apparently another thing Valentine was wrong about.

/break\

Magnus may have promised to help Jace up onto his feet, but neither of them seemed too invested in having that phase be outside the safety of Magnus' home. A few weeks had passed and Jace was still living with Magnus. He had quite found his place here, helping Magnus around the house – Magnus rarely bothered cooking, he usually just summoned food, he was too busy otherwise. Jace cleaned, cooked, helped Magnus out with strategies – to keep the merpeople safe. Magnus loved the company, the cave felt more like a home. Mostly, Magnus had wanted this time for Jace to accustom himself to being away from his abuser, to slowly dare more. Jace seemed to open up, he seemed to grow more comfortable, startled less easily. There were nightmares, most nights still. Magnus was watching over him, he was trying his best to help Jace.

It wasn't good to grow attached to little Shadowhunters. It was a _horrid_ idea to grow attached to the son of Valentine Morgenstern. Truly, tremendously bad idea. Yet here Magnus was, sitting on his couch, the TV on but Magnus' eyes were on Jace. The blonde was utterly transfixed on the TV – seemed Valentine didn't let him watch much TV and Jace really enjoyed trashy fantasy shows. It was adorable to watch him so enthralled with it.

"Why do you live in an underwater cave if you opt to have legs anyway?"

Magnus blinked a little and noticed that Jace was staring at his legs now, watching how Magnus bounced one leg, the other crossed over it. Tilting his head, Magnus turned fully toward him.

"Well, the dramatics for one. The customers for another. Not every merperson can change their shape. They wouldn't be able to reach me if I lived on the land", offered Magnus.

"...Huh. Guess that's right", whispered Jace, still staring at Magnus' legs.

"Miss my tentacles?", asked Magnus teasingly.

In a poof of blue smoke did his legs turn into his eight sleek, purple tentacles. Interesting, the way Jace's cheeks turned red as he stared intensely at Magnus' tentacles. Very interesting indeed. Leaning in some, Magnus reached a tentacle out for Jace, resting it on his thigh to pet it encouragingly. Blinking a few times, Jace lifted a hand to carefully touch it. He startled himself, jumping a little, before reaching out once more. His touch was gentle, careful.

"I meant... I just... since this is your home, I wasn't sure if you maybe turned human for my sake, since I'm human. I... was just wondering... if you maybe were trying to make things more comfortable for me and... you wouldn't have to. It's your home. I'm just your _guest_."

How adorable. Magnus smiled bemused at that. He wasn't actually thinking about Jace's delicacies, he was simply more comfortable with his legs when on land, because tentacles needed to be moist within a few hours so it was inconvenient to spend all his time out with his tentacles.

"You're welcome to stay here as long as you want", whispered Magnus softly. "I know you're waiting for the second shoe to drop, but... I've grown fond of you. You're good company."

"I _should_ go", argued Jace weakly, grasping the tentacle. "I should..."

"You should live the life you want", offered Magnus. "Go see the world. Travel. Fall in love. Laugh, have fun, start a family. I'm not stopping you. I'm simply offering you that if you're not ready for the world yet, you are welcome to stay here as long as you want."

"I can't thank you enough for all you've done for me, Magnus."

"Sweetheart, I'd still be locked into a tank on your father's ship without you", argued Magnus. "We help each other, as we said. And I do feel like we're pretty good at it."

Jace made a small noise that had Magnus smile amused. Though it was true. They did help each other. Magnus was providing Jace with a safe place to settle in and learn to adjust to an abuse-free life, while Jace took care of Magnus in a way he hadn't been taken care of in many, many years. The company, the food, the music – Jace was very good at the piano and Magnus found it incredibly soothing to listen to him. Jace had also soothed him through a few nightmares now. Admittedly, being tortured by Morgenstern's men for days was something he didn't just get over on his own. Jace knew, he understood, he simply... held Magnus, they didn't talk about it after.

/break\

Jace couldn't get Magnus' tentacles _out of his mind_. He couldn't stop thinking about them. He had sometimes thought about them before, but ever since Magnus had just... summoned them on the couch, ever since Jace had touched them for the first time – he couldn't stop thinking about them. The way they felt, both when he had touched them and the way they had felt on his thigh.

Things got decidedly worse when Jace had figured to just google it – the internet was a scary, weird, ugly place that Magnus had introduced him to. It was meant to help him figure things out – questions he may have about things that Valentine had kept out of reach for him. However, one thing Jace should not have googled was ' obsession with tentacles'. One of the first results was about Japan's obsession with tentacle porn and, naturally, Jace got confused and curious and he went down a slippery road of images and comics featuring women and men being molested and pleasured by tentacles. It definitely drove Jace even more mad because now he had an idea why he was so fascinated by the tentacles and he started thinking about them in a whole different light.

Now Jace's nights were haunted by the tentacles, wrapping around his wrists and ankles, holding him down, slithering all over his body, wrapping around his cock, pushing into-

Damn it. Yet another morning that Jace woke up covered in sweat, pants cum-stained and breath coming short as he came down from his orgasm. Gasping for breath, he ran his fingers through his hair. Those tentacles had a fascinating... strength to them. And they were so _thick_.

He took a cold shower, cleaning himself off all the cum and sweat and dirty thoughts. But once he was dressed, he felt more like himself. At least until he stumbled into the living room, where Magnus was sprawled out in a giant tub, some tentacles poking out. Really? He had just _composed_ himself and here Magnus was, all tentacles out. This was _indecent_. Jace flushed brightly.

"Mh, perfect. You're awake, so I won't have to get up", drawled Magnus pleased, reaching a tentacle out to wrap around Jace's wrist. "Would you get me a snack? I am _so_ comfortable right now."

"Sure... Anything in particular? Wait. Tentacles out, so... sushi?"

"Ye—es. Fish. You are a real darling", sighed Magnus contently, closing his eyes.

Jace knew, from the times Magnus left the cave and had to turn into a merman. Every time Magnus returned, he craved fish. The first time Jace had cooked, he had been a bit awkward about it, asking Magnus if he even _ate_ fish. Magnus had laughed at him and asked in return if Jace ate cow, or pig, considering they too were mammals just like Jace. Which, okay. It felt silly. Merpeople were the greatest predators of the ocean, of course did they hunt the animals of the ocean just like humans. And spending time in his merman-form always made Magnus crave mer-food, particularly fish.

Jace hummed softly to himself while preparing some fresh sushi for Magnus. He had gotten some recipes for fishes, but after trying a couple different things, he realized that Magnus had a particular taste for sushi then – probably because of the _raw_ fish.

"Breakfast is ready", announced Jace as he carried the sushi out.

"Mh. Perfect. You are _wonderful_. Tonight, it's my turn then, mh?"

Jace smiled faintly at that. Magnus always wanted to make sure that Jace didn't feel like a kept maid or something. Sometimes, Magnus would use his magic to summon them the greatest feast and Jace did usually let Magnus take care of the cleaning chores with some magic, unless Jace really needed the distraction and physical labor. Particularly when he woke up from a nightmare about his own abuse. Cleaning up helped ease his mind then; having a task to do.

"I'm going out to meet some... land-bound warlocks today. In New York City. Would you like to come with me? I think you need some... sun...", suggested Magnus. "Do a bit of shopping, actually eat in a fancy restaurant tonight perhaps? On me?"

"Like a date?", asked Jace without even thinking about it. "I didn't mean-"

"Mh... No, like a date. If you'd want it to be a date", interrupted Magnus softly.

He had a smile on his lips as he took another sushi piece, simply watching Jace and waiting. Date. An actual, real date? But – But Jace only lived here because of circumstances and because Magnus was very big-hearted. When Magnus had said he was growing fond of Jace, Jace hadn't expected _like this_ – like he wanted to date Jace. Dating was new. Jace had been sneaking around, sometimes, with the other teenage members of the Circle (mostly kids of other Circle members who were just as stuck in this as Jace). Dating. Dating Magnus Bane. Dating the guy he had been fantasizing about for weeks now. Dating the guy he was _living with_.

"I... I'd like that", nodded Jace after a moment. "Okay. A date. We're going on a date."

"Dress prettily", declared Magnus. "I mean, you'd look pretty in a potato sack so there's that."

"Well then, we could wear matching potato sacks and look stunning together?", suggested Jace.

Magnus laughed at that. It was a sound that Jace had come to really like.

/break\

The two of them went out for a shopping trip together, buying pretty new clothes and showing them off to each other. It was more fun than Jace remembered ever having. They had ice-cream before splitting up so Magnus could meet up with Catarina Loss, the High Warlock of New York. Not really knowing what to do, Jace wandered off toward the New York Institute. He didn't get too close, but he watched it from a distance. Watched Shadowhunters walk in and out. He didn't even notice how much time had passed until someone gently tapped his shoulder.

"Didn't even need a spell to find you. I had a... hunch you'd be here."

"Magnus. Your... meeting's already over?", asked Jace surprised.

"Already", echoed Magnus amused before sobering up a little. "You wanna go inside?"

"Inside? What. No. No, I can't. The Clave... No", muttered Jace and shook his head.

"You... sure? I've been wondering about this for a while. Do you want to go back to being a Shadowhunter? Do you... miss anything...?"

"I... Yeah. Sometimes, I do miss the fighting. Not the cause, but the fight. The purpose", whispered Jace. "I love your place. I've read half your library at this point. I enjoy spending time with you. I... do think that... staying home and adjusting has been important to me, but I... I think I _am_ getting restless. But... I _do_ like living with you. And I genuinely don't know if I'm ready to join society again. I _do_ know that I don't want to join the Clave."

"Mh... I do have maybe an idea or two. But let's talk about that over dinner. Our date still stands?"

"Ye—es. I am _starving_ ", agreed Jace with a smile.

When Magnus offered his hand, Jace slipped his into it and leaned into Magnus. He let the warlock lead the way. Walking and holding hands with Magnus felt strange. A good kind of strange though. The restaurant was a fancy one, candle light and soft music setting the mood. The two shared a salad, which felt incredibly silly but in a cute way. The wine went along well with the food too, though Jace let Magnus pick that, because he knew little about alcohol.

"You wanted to talk about something during dinner", noted Jace when the main course arrived.

"Ah. Yes. A... job-opportunity for you, if you'd like", replied Magnus slowly.

"A job? You'd have a job for me? And if this is some kinky maiden thing-"

"...Very tempting suggestion to combine household chores with fun, but no", interrupted Magnus, laughing softly to himself. "I've had many meetings with the merpeople under my protection. They are understandably worried about... Morgenstern. You... were trained by him, you know how they fight. I was thinking that maybe you could give self-defense classes. Who better to reassure my people by teaching them how to protect themselves than someone who knows first-hand _what_ they'll need protection from exactly. Do you think that is something you'd be interested in?"

"I... I _have_ been training the younger Circle members for a while now", whispered Jace thoughtfully. "But... wouldn't there be one big problem...? Or rather, two?"

He wiggled his feet in emphasis, making Magnus chuckle. "Blondie, you are literally living with the most powerful magic-user this side, and inside, of the ocean."

"...Are you suggesting a reverse Ariel here?", asked Jace surprised.

"I can give you a tail, yes. But you won't have to give up your voice", assured Magnus. "So?"

"I'd... like to give it a try, yeah. That sounds... nice."

It sounded more than just nice. It'd also be a way to reintegrate into society – but a much less scary society than that of the Shadowhunters. He didn't even know if he'd ever fit in with humans. Well, he also didn't know if he'd fit in with merpeople, but it seemed much less intimidating than trying to adapt to the mundie ways. And he'd have _Magnus_. Smiling softly to himself, Jace stretched one leg out to nudge Magnus' underneath the table. The teasing grin he got in return was followed by – Jace yelped as something crawled up his pant-leg. A tentacle. Jace's eyes widened.

"Don't tease if you can't take the pay-back, sweetheart", warned Magnus.

"Oh, I can take it", declared Jace confidently.

"Mh... you can... _take_ it, mh?", asked Magnus, his voice dropping in a low lull.

"I... I..." Jace paused and swallowed hard as the tentacle around his ankle tightened a bit.

"I wonder just _how much_ you could... take..."

It made Jace huff a little. Magnus really was a tease. And Jace... really enjoyed that.

/break\

The teasing increased as the two of them dated longer. It helped that Jace was slowly getting out of his shell. After their first date, Magnus started occasionally taking Jace with him to the mundie world, but more importantly to the underwater cities. Magnus swore that he had absolutely not picked the tail, the magic simply adjusted Jace's physical form and turned him into what he would look like as a merman. Still Jace didn't buy that because his tail was _golden_ , sparkly and pretty. That was absolutely something that Magnus Bane would do on purpose.

The spell was easy enough; if Jace submerged in salt-water, his legs turned into a tail. Magnus had specifically designed it that way so Jace could come and go as _he_ pleased and wouldn't have to depend on Magnus being home to turn him back and forth. The first time going to an underwater city and meeting merpeople had been, admittedly, a bit scary. But Magnus had been there, had _stayed_ with him the whole time. Watched the class. There had barely been very few daring enough to sign up the first time around. Many were wary, because he was human – he was a Shadowhunter – he was Valentine's son (though Magnus had decided to keep that one on the down-low for now).

Jace's student-body grew with every session. By now, so many young and older merpeople had signed up that they had to schedule _multiple_ classes. The kids downright adored him and he had actually made some friends among the adults in some of his classes, as well as some other teachers.

Over time, Jace started leaving the house for more than just classes. To browse the city, do some shopping, hang out with the friends he now made.

Magnus and Jace also went on their dates in town now, or simply on walks together. Magnus made him feel understood, he made him laugh. The two of them were growing closer and closer. Which included their sex-life. It was nice, Jace was only used to quick handjobs in dark broom closets. Now he got slow handjobs in the living room, fucking on the couch, blowjobs in the shower. However, that did not make things _easier_ , because now that Jace knew what Magnus' cock felt like inside of him, he kept wondering about certain _other_ parts...

Jace was still being tortured by dreams of Magnus' tentacles. However, he had _no idea_ how to suggest it, because all things he saw on the internet considered, it was weird. Yet he couldn't stop thinking about those eight, sleek, strong tentacles. Even more so nowadays, because he got to see Magnus' merman-form far more often. Like right now, as they strolled the streets together.

Magnus was holding onto one of Jace's hands with a tentacle, another tentacle gently resting against Jace's flank. They were _very_ touchy-feely. Most of that was supposedly on instinct; it was hard to consciously control all of those eight limbs, so sometimes they just reached out on instinct to hold onto important things. Jace was, apparently, a very important thing. He could live with that.

"So, how was your day so far, sweetheart?", asked Magnus curiously.

"Did some groceries shopping – don't roll your eyes, we gotta support the local shop-keepers too, can't just summon everything with your magic", huffed Jace. "Oh, right. Here."

Magnus blinked confused as he was being handed a little glass figurine. It was an octopus, the glass of the tentacles dyed black. The cute thing was that the two frontal tentacles formed a heart.

"What's that?", asked Magnus confused.

"Well, I just... I got my first paycheck for the classes. I... It felt awkward buying you something from your own money. So, I... I saw this a while ago already and asked the shop-keeper to put it aside for me so I could buy it from my first paycheck", explained Jace. "It's a gift."

Magnus made a small sound in the back of his throat. A gift. It had been a long while since someone had given him a _gift_. He carefully pocketed the figurine, putting a protective spell on it to make sure it'd survive until they got back home. Smiling, Magnus leaned in to kiss Jace's cheek.

"You're adorable, little Shadowhunter", whispered Magnus. "Thank you."

"Shut up", grumbled Jace flustered.

"And so mature about accepting compliments about anything but your looks."

Magnus smiled teasingly at him. Jace noted there were two more tentacles on him now.

"Clingy warlock", whispered Jace fondly, caressing one of the tentacles softly.

"Ah. I'm sorry, you mentioned that before." Magnus laughed sheepishly, trying to remove it.

"No. I'm not... that wasn't a complaint", muttered Jace flustered, reaching out for Magnus' tentacle. "I was just _curious_ about it before. And I... like the... clingy. Especially in the mornings."

"That's called cuddling and I have _noticed_ that you're very cuddly", chuckled Magnus. "So... this _is_ alright? I _am_ still unsure about how comfortable you really are with my tentacles."

" _Very_ ", declared Jace quickly, his cheeks darkening.

"Mh... interesting answer. Well, how about lunch for now?", suggested Magnus.

"I _could_ eat something", agreed Jace, relieved that Magnus was changing the topic.

/break\

They were in bed together, a few days later, when Magnus decided to bring it up again. Magnus woke up first, his blonde Shadowhunter tucked under one arm. Last night had been incredible, both had been exhausted and just fell asleep together. There was something that Magnus wanted to _suggest_ to Jace, a hunch he had for a little while now. Smiling, Magnus traced Jace's face gently. He was so adorable when he was asleep – peaceful. Both of them had decidedly fewer nightmares when they shared a bed. It was how they had first started sleeping together like this. After yet another nightmare that Jace woke Magnus up, the two had fallen asleep side by side. Now, Jace didn't really leave for his room anymore at all, though Magnus still kept it the way it was, to give Jace a room to retreat to when he needed the distance and alone time.

"Stop staring dreamily at me while I'm asleep", grumbled Jace teasingly.

He blinked slowly and looked up at Magnus with a soft smile. Leaning in, Jace kissed Magnus' cheek. Huffing, Magnus pulled his lover closer, resting his arms around Jace's waist, hands on top of his butt. Jace smiled at him as he adjusted to lay on Magnus' chest.

"You're cute when you're asleep, it's not my fault", huffed Magnus defensively.

"Do you have anything to do today? It's my day off", asked Jace softly.

He sat up a bit, straddling Magnus' hips, his hands on Magnus' chest. "Unless there's any emergency caller, I am _all_ free all day. There was so much to do this week, I deserve a day to myself."

"Does yourself involve your boyfriend?", wondered Jace, kissing Magnus softly.

"I _do_ love involving myself with my boyfriend. And... I... would have some... _ideas_..."

Magnus let his hands slowly slip down along Jace's thighs, squeezing. Jace was grinning as he leaned down to slowly kiss along Magnus' neck, down to his chest. He could feel Magnus' hands, running back up to Jace's waist. Tilting his head, Magnus reached out to grasp Jace's neck and pull him down into a slow, deep kiss. Magnus' hands wandered down Jace's back, tracing his spine and the strong muscles beneath the taunt skin. Though he paused when their kiss ended.

"I wanted to... ask you something, sweetheart", started Magnus cautiously. "About your... let's call it _fascination_... with my tentacles. Just how curious are you?"

"By the Angel, you looked at my browser history", whispered Jace mortified. "I can explain-"

"I did _not_ look at your browser history. When I gave you that tablet, it was meant to be _yours_ and I respect your privacy. However, _now_ I do have some questions", interrupted Magnus curiously.

Jace leaned back again, farther than before. He supported himself with one hand, rubbing his neck with the other as he tried to not look at Magnus. The way his cheeks flushed was delightful.

"I have been obsessed with your tentacles. And I didn't really understand what it was at first so I tried to google it. That... only brought me to some very... explicit... porn", admitted Jace, flushes dark-red. "Which was not helpful. But I've been... reading a lot of these Japanese comics..."

"Oh my god, you're reading tentacle porn", whispered Magnus in awe. "That is adorable."

"Adorable", muttered Jace, looking nearly offended. "You're a strange one, Bane. Stop always calling me 'cute' and 'adorable'. I'm a fierce Shadowhunter with killer instincts."

"Who is currently _pouting_. You're adorable, babe, stop denying it", chuckled Magnus.

He pulled Jace down into another kiss, rolling them over just a bit. Just enough for both of them to be laying on their sides, facing each other. Slowly, smoke started to cover Magnus' lower half and when it disappeared, his two legs were replaced by eight tentacles. Jace made a small noise.

"Wait. _Really_? I mean. Are you... sure? Are you really suggesting what I think you're suggesting...?"

"Only if you _want_ to... try this. But yes, personally I do enjoy using my tentacles during sex. It's an intense sensation for me and so far, my partners have been enjoying it too", offered Magnus.

Magnus stayed perfectly still, aside from the occasional wiggle of a tentacle or two, waiting for Jace to consider and process. Thoughtfully did Jace reach out. His fingers skipped over where Magnus' skin turned pitch-black, where his tentacles split off. Slowly did he trace one tentacle. Magnus curled it up, allowing Jace to trace it to the tip. Adorably enough, Jace poked the tip as he reached it.

"...I _really_ want this. Don't take my reluctance as a no. I just... the porn is one thing but I'm unsure how this is going to go down in real life so... take it slow?"

"Of course, sweetheart", promised Magnus gently, kissing Jace's cheek. "Nice and slow."

One of his tentacles wrapped around Jace's right thigh, gently pushing it out of the way, spreading Jace's legs. It held the leg up, while another tentacle teasingly wrapped around Jace's already half-hard cock. Jace shuddered when a third and fourth tentacle explored his chest. The suckers felt amazing, the way they latched onto his skin, sucking just a bit, leaving small marks in their wake. A fifth tentacle was teasing his balls, the sixth tentacle had reached up to caress Jace's cheek. It was a lot, so much touch all at once. But it was a good kind of much. The kind of much that put him on edge and made him arch his back, wanting more. The sixth tentacle was curling around Jace's chin now, tilting his head back so Jace could look at Magnus. Those golden eyes would never stop turning him on, really. The way he'd look at Jace, so all-consuming.

"Tell me if there is anything you _want_ ", requested Magnus. "I don't just want to try thing and have you freak out on me, my little Shadowhunter."

"I... want to try... uhm", Jace paused and cleared his throat. "Taste it. If that's not weird."

"Not more weird than a blowjob", assured Magnus with a smile.

The tentacle around Jace's chin unfurled and reached up, gently tracing Jace's lips. Jace eagerly opened his mouth for it. It slithered in and at first, Jace found the sensation odd, however Magnus was right in the end, it wasn't _that_ different from a blowjob – he was taking someone else's body part into his mouth, for the sake of pleasure. It was... It tasted _good_. Sweet. There was like a sheet of something delicious and slick on it and without thinking about it, Jace started sucking it off, greedily. Magnus moaned at that, thrusting more of his tentacle into Jace's mouth. Another tentacle reached around Jace's waist, parting his butt-cheeks for the final tentacle to reach in. It poked against Jace's hole, slick with whatever tasted _so good_. It made him shudder, something about the slick felt very different down there. The tentacles playing with his dick and balls too, slick and hot.

Jace moaned around the tentacle in his mouth that went deeper and deeper, filling his cheeks out too. It tasted _so good_ , so addictive downright. The tentacle poking his hole was slowly breaching, pushing in. It helped that the tips were thin and it slowly got thicker and thicker. The tentacle on his ass squeezed it tightly, making Jace shudder. The feeling of the tentacles all over his body made him feel so overwhelmed, he reached out to cling onto Magnus and Magnus held him.

"Sh, it's okay. You're fine. Squeeze my hand if you need a break", requested Magnus.

He linked their fingers and waited for a moment, but Jace simply shook his head. Smiling pleased, Magnus leaned in to kiss Jace's forehead. One of the tentacles exploring his chest moved back to Jace's ass too, slowly easing in alongside the other. Jace gasped breathlessly as he was being filled by two. The intense feeling the slick caused grew even more and Jace moaned helplessly, still sucking on the tentacle in his mouth. The two tentacles up his ass alternated in their thrusting, pushing in deeper and stretching him more, yet Jace still wanted _more_. He whined soflty, tugging on Magnus' hair with the hand around Magnus' neck. Magnus hummed curiously.

"Do you want more? Are you this greedy already?", chuckled Magnus amused.

Jace nodded enthusiastically and was rewarded by a third tentacle pushing into his ass, spreading him more than anything _ever_ had, anything he ever even could imagine spreading him. At the same time, a second tentacle was pushing between Jace's lips and Jace moaned pleased as he got twice as much of the delicious slick. One tentacle was still holding his leg up by the thigh, the remaining two still playing with Jace's cock and balls. The sensation of the suckers alone was already a lot, but the way the tentacles could squeeze down and rub him. Every time Jace was close, Magnus' tentacle squeezed down the base and keep him from coming. But now – now, with _everything_ – Jace really wanted to come. He opened his eyes, not even having realized he closed them, looking at Magnus. That look was everything Magnus needed to know what Jace wanted. Smiling, Magnus eased off around Jace's cock, jerking him off for real now, while the three tentacles assaulted Jace's prostate repeatedly, thrusting in and out harshly. Jace came hard, shooting his cum in a huge arch over them before collapsing onto the bed. When Magnus came however, Jace was left choking. Literally so due to the two tentacles in his mouth, but also by the surprise alone. All eight of the tentacles started to produce a huge amount of the addictive slick, filling Jace's mouth and ass and also covering his body wherever they touched him. Magnus carefully pulled out, gently caressing Jace's cheek.

"So, was it as good as the porn?", asked Magnus teasingly when he kissed Jace.

" _Better_. The _taste_ -", groaned Jace, snuggling up to Magnus.

"It's an aphrodisiac. To heighten our mate's pleasure", whispered Magnus.

He wrapped his arms and tentacles around Jace to pull him close, kissing his mate's forehead.

_~*~ The End ~*~_

**Author's Note:**

> The prompt "eight" HAD to go to tentacle sex. It just had to. And I can't believe I've never written octopus merman Magnus before! :D


End file.
